3.5 Real numbers
When we’re were done looking at the real numbers we’ll have finished analyzing the typical numbers most people encounter. Let’s begin with decimals.
3.5.1 Decimals
A decimal expression for a real number looks like
- an optional minus sign,
- followed a finite number of digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9,
- followed by a period, also called the decimal point,
- followed by a finite or infinite number of digits.
In many parts of the world, the decimal point is a comma instead of a period, but I use the United States and UK convention here.
If there are no digits after the decimal point then the decimal point may be omitted.
Any trailing 0s on the right are usually omitted when you are using the number in a general mathematical context. They may be kept in situations where they indicate the precision of a measurement or a numeric representation in computer code.
Any leading 0s on the left are usually omitted. We have
